Conveyors are used in the manufacture of plastic blow-molded bottles to transport the bottles ejected from a blow molding machine to cooling and processing stations. A bottle conveyor typically includes a conveyor belt or chain moving through straight conveyor sections joined by curved conveyor sections. Guide fences extend along both sides of the conveyor to stabilize the bottles and to ensure the proper orientation of the bottles during transportation and processing. The spacing between the fences is adjustable to enable the conveyor belt to convey different sized bottles of varying size and capacity.
Adjusting the spacing of a curved fence may be accomplished by rotating the fence around an axis of rotation. This changes the vertical position of the fence with respect to the conveyor belt. Other curved fences are adjusted by translating the curved fence along a linear axis towards and away the other curved fence. The inner and outer curved fences may not remain concentric with each other and so the radial spacing between the curved fences may vary along the circumferential length of the fences. Yet other curved fences are adjusted by radial movement of a number of arc segments. Such fences are mechanically complex, and it can be difficult to present a smooth guide surface to the bottles moving along the fence. And yet other curved guide fences rely on tensile forces being present across the cross-section of the fence along the length of the fence to elastically deform the fence. These curved fences are limited to use where only relatively small changes in radius (for example, one or two millimeters) are required.
Modern conveyors include a flexible conveyor chain that enables the chain to make relatively sharp, small radius turns between straight sections. Known adjustable curved fences do not offer the adjustment capabilities needed for relatively sharp conveyor turns. Furthermore, bottles are no longer simply round; bottles have become more complex in shape and often require an adjustable curved fence that does not change vertical height and can provide relatively constant radial spacing between the inner and outer curved fences throughout its adjustment range to assure proper orientation of the bottles as they move through the curve.
Thus there is a need for an improved adjustable curved fence assembly for use with modern flexible chain conveyors.